The incidence of congestive heart failure (CHF) is increasing worldwide with over one million new cases diagnosed annually. Over the past 30 years, counterpulsation with an intra-aortic balloon pump (IABP) has been widely and successfully used as a short-term treatment for cardiac dysfunction. However, counterpulsation is limited by its location within the descending thoracic aorta to short durations of therapy, typically less than 14 days. To overcome this limitation, Superficial Counterpulsation Research (SCR), Inc. has invented a novel device for long-term application of counterpulsation therapy for heart failure. The counterpulsation device (CPD) is designed to be implanted via a surface operation in the shoulder area (pacemaker pocket) by attaching it to the subclavian artery. This approach would give the patient nearly complete mobility. The first prototype CPD developed was a 40-ml valveless sac that fills and empties with each cardiac cycle. In acute studies in a calf with diminished cardiac function (DCF), the 40-ml CPD successfully reduced ventricular workload and augmented myocardial perfusion. In a cadaver fit study a problem with proper fit of the device in patients was revealed. To solve this problem, a smaller, second generation device (30-ml CPD) was developed. The 30-ml CPD provides a better fit and more comfortable implantation in the shoulder area, but its stroke volume is reduced by 25%, and this change requires verification that it can provide sufficient hemodynamic support. This 30-ml CPD is ready for in vivo testing. The goal of this Phase 1 SBIR proposal is to compare the hemodynamic efficacy of the new, ergonomic 30- ml CPD to the 40-ml CPD prototype. We will also demonstrate that the 30-ml CPD will not damage the artery or blood. This will be accomplished by completing the following specific aims: Aim-1: Demonstrate the efficacy of the 30-ml CPD in reducing ventricular workload and augmenting diastolic perfusion to the heart and vasculature in acute experiments using the DCF calf model. Aim-2: Perform a safety evaluation of the 30-ml CPD by examining possible pathological and hematologic changes in the artery and blood (i.e. hemolysis). In Phase II, we will propose chronic in vivo testing (30-day and 90-day DCF calf model) to demonstrate long-term effectiveness of the 30-ml CPD. [unreadable] [unreadable]